Method of manufacturing spherical light weight containers



Aug. 29, 1939. w. H. FREYGANG 2,171,111 7 METHOD or wurfAc'r-unmc SPHERICAL LIGHT WEIGHT con'ruszns Filed Feb. :5; 1936 Frame 3 INVENTOR BY WALTER H. FREYGANG A 'oRNEv Patented Aug. 29, 1939 PATENT OFFICE METHOD OF MANUFACTURING SPHERICAL LIGHT WEIGHT CONTAINERS Walter H. Freygang, Essex Fells, N. J assignor to Walter Kidde & Company, Inc., Bloomfield, N. J., a corporation of New York Application February 3, 1936, Serial No. 62,027

8 Claims.

The present invention relates to containers for the storage of fluids under high pressure and more particularly to the method of manufacturing such containers. More specifically the invention relates to the manufacture of spherical containers which are extremely light in weight but which have greater relative strength in proportion to the weight of metal used than the relative strength of the containers which are now available. 1

Containers in which it is possible to store a fluid underhigh pressure, such as carbon dioxide at a pressure of 1000 pounds per square inch or more, have long been known. These containers have l5 made it possible to supply carbon dioxideunder high pressure on airplanes, particularly for fire extinguishing, and for flotation in the event that an airplane alights on a body of water. Several containers which would withstand the high pressure and which have not been too heavy have been made and employed on airplanes. However, the problem of making these containers still lighter in weight has now presented itself.

It is a well known scientific fact that the stress in a transverse section of a cylindrical container is one half of the stress in a. longitudinal section of such a container. It is therefore readiiy apparent that if a container is made of such a shape that there can be no longitudinal stress set up,

the weight of material necessary to make such a container may theoretically be out in half. The shape of such a container must necessarily be spherical since a spherical container provides no walls in which a longitudinal stress may be set' Hitherto'the containers. have been formed as containers open at one end and closed at the other from plates or billets by drawing. The containers have then in accordance with various 4o methods and processes been closed at the open end and prepared to receive a coupling for the delivery pipe, nozzle or valve. Such containers in their final form have been cylindrical in shape. To take an ordinary open ended cylinder and subject it to a process by which it would be formed into a light weight spherical container of great strength has often been desired but it has been impossible'to do so because of the impossibility of holding the cylinder while it was being machined and shaped into a sphere. Accordingly it is an object of the present invention to provide a method of manufacturing spherical containers from an open ended cylinder.

It is a further object to provide a method 01 holding the container while it is subjected to the finished spherical container.

various steps and processes necessary to form It-is a further object to provide a spherical container in which the weight of metal used in the walls of the container is greatly reduced 3 tainer of Figure 2.

Figures 4 and 5 are views similar to Figure 2 and illustrate successive steps in the formation of the container.

c Figure 6 is a view in longitudinal section of a 20 completed container.

One method in which the objects of the present invention may be accomplished is illustrated in Figures 1 to 6. A cylinder is formed either from a plate or from. a billet by successive drawing. '5 The cylinder of Figure 1 is open at one end 3,

. closed at the other end 5, and has a substantially uniform diameter from one end to the, other. In this form, the wall thickness, shown by the distance between the inner surface I of the cylinder 30 and the outer surface 9 of the cylinderis greatly in excess of that required to safely store high pressure fluids such as carbon dioxide.

Since there is a great excess of metal in the wall of the container the thickness of the metal 35 must be reduced. The reduction may be accomplished by machining. By the term machining is meant any material removing operation such as cutting, abrading, turning, grinding, and the like. In order toreduce the thickness, part of 40 the'metal is machined away from the inside of the cylinder to form ,a new inner surface H. The dotted line 1, in Figure 2, indicates the, position of the internal surface 1 before the cylinder has been machined internally. The 4.5 amount of metal removed from the interior of the container is comparatively slight and it is preferable to remove the greater amount of excess metal from the exterior of the cylinder. In

'fact, in many instances it may be desirable to 50 remove all of the excess metal from the outer surface and to leave the inner surface untouched. The sequence of the machining steps, may, of course, be varied, either the exterior or the interior of the cylinder may be machinedflrst, 55

or only the exterior may be machined, without affecting the product or method herein set forth.

When the excess metal is to be removed from the outer surface of the cylinder the entire outer surface of the cylinder is not machined, only that portion which lies between the circumferential line l3 near the open end 3 of the cylinder to a circumferential line I5 on the closed end 5 being removed. The portion of the cylinder from which metal is removed is shown by the space between the dotted line 9, which shows the position of the external surface before machining, and the new surface l1. It will be noted by reference to Figure 2 that the failure to machine the entire surface of the end 5 will create a chucking lug I9. The sole purpose of the chucking lug i9 is to furnish the means by which the cylinder may be held during the remainder of the operations. It is through the means of the chucking lug that the cylinder may be held when the open end of the cylinder is closed in as is indicated at 2! in Figure 4. The chucking lug l9 may be used in numerous ways to hold the container. For instance, holes may be drilled through'the lug so I that keys or pins may be driven through the holes to attach the container to a cutting machine, etc., or flats may be ground or milled in the circumference in order that the lug may be gripped in the jaws of the machine in which the container isbeing made. A variety of methods for using this chucking lug in holding the container during the various operations will suggest themselves to those skilled in the art.

The closing in does not decrease the wall thickness, in fact it will cause a slight thickening. Thus a relatively short neck is provided on which any stamping that may be required is placed without impairing the strength of the cylinder. Any excess thickness may of course be removed from either the outer or inner surface of the spherical container.

The closing in operation will probably leave an uneven central open ng. However, the fact that there is an excess of material around the neck of the container permits any metal which is undesired to be machined away and the neck squared off as at 23in Figure 5. The central opening 25 may then be threaded internally in order to be ready to receive a coupling for the delivery pipe, nozzle or valve which is placed on the container to permit regulation of the discharge of the contents of the container. It is readily apparent that the container is held throughout any of these operations by the chucking lug.

When the spherical container has been completely formed and the excess material has been removed, the final operation which is necessary to complete the spherical container as illustrated in Figure 6 is to machine off the chucking lug l9, since there is no further use for it.

While the invention has been described with a circumferential line near the closed end to a circumferential line near the open end, said chucking lug serving to hold the container during pressure and having one end closed in, reducing the wall thickness of the cylinder and forming a chucking lug on the closed end of the cylinder by removing metal from the external surface of the cylinder leaving suficient thickness at the end to be closed in to permit proper closing in, closing in the cylinder to form a spherical container by holding the chucking lug, removing metal from the surface of the walls to a minimum wall thickness to withstand a predetermined high pressure, and removing the chucking lug.

3. The method of making high pressure spherical metal containers for carbonic acid gas and. the like with at least one end closed in which consists in forming by successive drawing operations a cylinder with wall thickness greater than necessary to withstand the high pressure, reducing the thickness of the cylinder by removing metal from a surface thereof from a circumferential line near an end to be closed-in toward a circumferential line near the closed in end to form a chucking lug thereon by which the container may be held during the subsequent operations, closing the cylinder from adjacent the first circumferential line to said end to be closed in, and removing metal from the outer surface of the container to a predetermined wall thickness and removing said chucking lug to form the spherical container.

4. The method of producing a high pressure spherical metal container with a closed bottom and open at the other end and having walls of minimum thickness for a predetermined high pressure from a cylinder closed at one end formed by successive drawing operations and having a substantially uniform excessive wall thickness, by forming a chucking lug on the closed end of the cylinder by removing metal therefrom, holding the cylinder by means of the lug, and closing in the open end of the cylinder to form a spherical container and removing all excess wall thickness and removing the chucking lug.

5. The method of making high pressure spherical meta l containers for carbonic acid gas and the like with at least one end closed-in which consists in forming by successive drawing operations a cylinder with suflicient thickness at an end to be closed-in to permit closing-in and of a wall thickness greater than necessary to withstand the high pressure, reducing the thickness of the cylinder by removing metal from a surface thereof and forming a chucking lug on the closed-inend thereof, chucking the container by means of the lug, closing-in an open end of the cylinder, and removing metal from the walls of the container to a predetermined thickness and removing the chucking lug.

. 6. The method of producing a high pressure spherical metal container from a cylinder open at one end and closedat the other formed by successive drawing operations and having a substantially uniform excessive wall thickness, by removing metal from the external surface of the closed end to form a chucking lug thereon, holding the container by means of the chucking lug, closing in the open' end to form a spherical container, reducing the walls of the container to a predetermined thickness by removing metal from at least one surface thereof, and removing the chucking lug. 4

'1. The method of producing a high pressure spherical metal container from a cylinder open at one end and closed at'the other formed by successive drawing operations and having a substantially uniform excessive wall thickness, by combined metal removing and closing in operations, metal being removed both from the external surface of the closed end to form a chucking lug thereon and from at least one of the surfaces of the wall of the container to reduce the wall to a predetermined thickness.

8. The method of producing a high pressure spherical metal container froma cylinder open at one end and closed at the -other formed by successive drawing operations and having a substantially uniform excessive wall thickness, by removing metal from the external surface of the closed end to form a chucking lug thereon, holding the cylinder by means of the chucking lug, and forming the cylinder into a spherical container of predetermined wall thickness by combined material removing and closing in operations.

WALTER H. FREYGANG. 

